It’s a recurring debate for the past few years: teenagers need enough sleep, so why don’t we start school later. Insufficient sleep during the week, and attempts to catch up at the weekend lead to ‘social jet lag’, but delaying school start times is unlikely to reduce sleep deprivation in teenagers, according to this new study by 2 mathematicians and don’t worry also sleep scientists were involved. And they also suggest a solution: turning down the lights in the evening would be much more effective at tackling sleep deprivation.